Fixed some stuff in hack branch

Fixed some fatal issues in hack lang.
@Swahvay make sure your test isn't in the global scope. That gives me: `test.php|5 col 9 error|  This call is invalid, this is not a function, it is a string (Typing[4009])`. `fun()` (not func) is needed to turn the string to a correctly-typed callable, and is builtin to HHVM.

@steelbrain Not only do you need to correct this to use [`fun`](http://docs.hhvm.com/fun), but it only works with literal strings. These changes won't be throwing errors in Hack since the file is only partial.